GSM ppt

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					     Presentation on six months Industrial
           Training undertaken at




Submitted by:-
Chanjot Singh
Univ Roll No. 6120405841
College Roll No. 606/06
                 COMPANY PROFILE
• Nokia Siemens Networks is one of the largest telecommunications
  solutions suppliers in the world.
• Nokia Siemens Networks was created as the result of a joint
  venture between Siemens COM division (minus its Enterprise
  business unit) and Nokia's Network Business Group. The new
  company was announced on 19 June 2006.
• Nokia Siemens Networks operates in approximately 200 countries
  worldwide, and has about 60,000 employees. Its major
  manufacturing sites are in China, Finland, Germany, Poland and
  India.
• About 1 billion people are connected through its networks.
• It is foreseen that, at a combined revenue of more than € 15 billion,
  the new company would be one of the largest telecommunication
  equipment makers in the world.
                   CONTENTS

•   GSM Basics
•   GSM System Architecture
•   Identities used in GSM
•   GSM Channels
•   Mobility management
•   Call management
•   Abis mapping
•   Drive test
•   Troubleshooting
             Background to GSM
• 1G : Advanced Mobile Phone Service (AMPS)
       Analog, Circuit Switched, FDMA, FDD
• 2G : Digital Advanced Mobile Phone Service (D-AMPS)
       Digital, Circuit Switched, FDMA, FDD
• 2G : Global System for Mobile (GSM)
       Digital, Circuit Switched, FDMA and TDMA, FDD
• 2G : Code Division Multiple Access (CDMA)
       Digital, Circuit Switched, FDMA, SS, FDD
           GSM System specifications
Frequency band
          Uplink               890 - 915 MHz
          Downlink             935 - 960MHz
Duplex Frequency Spacing       45MHz
Carrier separation             200KHz
Frequency Channels             124
Time Slots /Frame(Full Rate)   8
Voice Coder Bit Rate           13Kbps
Modulation                     GMSK
Air transmission rate          270.833333 Kbps
Access method                  FDMA/TDMA
Speech Coder                   RPE-LTP-LPC
         GSM uses paired radio channels




890MHz            915MHz    935MHz        960MHz




  0                   124    0             124
FDMA-TDMA
                 GSM Architecture

It provides an overview of the GSM network architecture.
    This includes a brief explanation of the different network
    subsystems and a description of the functionality of the
    elements within each of the subsystems.
• General architecture overview
• The Mobile Station (MS) Subsystem and Elements
• The Base Station Subsystem (BSS) and Elements
• The Network Subsystem (NSS) and Elements
              Base Station Subsystem

The BSC:
• Allocates a channel for the duration of a call
• Maintains the call:
      monitors quality
      controls the power transmitted by the BTS or MS
      generates a handover to another cell when required

The BTS:
• Provide radio access to the mobile stations
• Manage the radio access aspects of the system
               BSS Configuration

• Collocated BTS

• Remote BTS

• Daisy Chain BTS

• Star Configuration

• Loop Configuration
Collocated BTS: BTS is situated along with BSC or the
  MSC and no additional E1 link is required.




                               BTS



                          BSC
Remote BTS : BTS is situated in a stand alone position and
  additional E1 links are required to connect to BSC.




                                    BSC
             BTS
         Daisy Chain


          BTS 3

 BTS 1              BTS 4




              BSC
BTS 2
                            MSC
   Star Configuration


            BTS 3

 BTS 1


            BSC
                          BTS 4




BTS 2               MSC
         Loop Configuration


              BTS 3

 BTS 1




                              BTS 4




                  BSC

BTS 2                             MSC
                 Network Subsystem
• Can be considered as a heart of the GSM Network.
 All the major activities like
• Routing,
• Security functions,
• Call handling, charging,
• Operation & maintenance,
• Handover decisions,

• Various kinds of interfaces are used to communicate between
  the different entities. Different methods are used to optimize
  and provide the quality network with the minimum operating
  cost.
         Mobile Switching Center (MSC)

•   Performs call switching
•   Interface of the cellular network to PSTN
•   Routes calls between PLMN and PSTN
•   Queries HLR when calls come from PSTN to mobile user
•   Inter-BSC Handover
•   Paging
•   Billing
        Home Location Register (HLR)

• Stores user data of all Subscribers related to the GMSC
   – International Mobile Subscriber Identity(IMSI)
   – Users telephone number (MS ISDN)
   – Subscription information and services
   – VLR address
   – Reference to Authentication center for key (Ki)
• Referred when call comes from public land network
  Visitor Location Register (VLR)
• Database that contains Subscriber parameters
  and location information for all mobile
  subscribers currently located in the geographical
  area controlled by that VLR
• Identity of Mobile Subscriber
• Copy of subscriber data from HLR
• Generates and allocates a Temporary Mobile
  Subscriber Identity(TMSI)
• Location Area Code
• Provides necessary data when mobile originates
  call
           Authentication Center (AuC)

• Stores Subscriber authentication data called Ki, a copy of
  which is also stored in in the SIM card
• Generates security related parameters to authorize a subscriber
  (SRES-Signed RESponse)
• Generates unique data pattern called Cipher key (Kc) for user
  data encryption
• Provides triplets - RAND, SRES & Kc, to the HLR on
  request.
    EIR (Equipment Identity Register)
• EIR is a database that contains a list of all valid mobile
  station equipment within the network, where each mobile
  station is identified by its International Mobile Equipment
  Identity(IMEI).
• EIR has three databases.,
   – White list - For all known,good IMEI’s
   – Black list - For all bad or stolen handsets
   – Grey list - For handsets/IMEI’s that are
                on observation
     Transcoder and Rate Adaptor Unit (TRAU)

The primary function of the TRAU is to convert 16kps GSM
  speech channels to 64kbps PCM channels in the uplink
  direction and the reverse in the downlink direction.

The reason this process is necessary is because MSCs only
  switch at the 64kbps channel level.
                    TRAU Locations
TRAU can be physically located in the BTS, BSC or MSC
  and hence leads to a variety of installation configurations.
                  Interfaces between components
     MS
           Um

                   BTS                                         VLR                     HLR

                                 BSC
                         Abis                 MSC
                                       A                 B                                 H
MS                                                                          C                    AuC
            BTS                                                      GMSC
                                                         E                      F
                    Abis
                                                                                           EIR
                                       A                 E
                                              MSC

                           BSC                                                      PSTN
     Um
          BTS                              X.25
                                                   VLR
                                  X.25
                                                  OMC Server
                    Abis Mapping

Besides the traffic channels, the Abis interface also carries the
  required signaling information in 64 Kbit/s channels. One
  signaling channel is normally provided for each transceiver
  within a BTS for controlling upto 8 subscribers per carrier
  frequency.
          Sig TRX 2
      0     1   2     3

      4     5   6     7    TRX 2

BSC

                          TRX 1
          Sig TRX 1
      0     1   2     3

      4     5   6     7




            TS 0
TS     BTS 1            BTS 2
 0   PCM Management Information
 1     TRX 1
 2     TRX 1
 3                      TRX1
 4                      TRX1
 5     TRX 2
 6     TRX 2
 7                      TRX 2
 8                      TRX 2
 9     TRX 3
10     TRX 3
11                      TRX 3
12                      TRX 3
13     TRX 4
14     TRX 4
15                      TRX 4
16                      TRX 4
17     TRX 5
18     TRX 5
19                      TRX 5
20                      TRX 5
21     TRX 6
22     TRX 6
23                      TRX 6
24                      TRX 6
25     Signalling BTS1, Sector1
26     Signalling BTS1, Sector2
27     Signalling BTS1, Sector3
28     Signalling BTS2, Sector1
29     Signalling BTS2, Sector2
30     Signalling BTS2, Sector3
31           Control Ring
TS Arrangement on PCM Link :

1 Sector occupies             2TS for TCH (64 Kbps)
                              1TS for signaling

Total number of Time slot in one PCM          32
Out of which 1 is used as sync and other for internal
  signaling.

TS available for carrying the information    30

Therefore total number of TRXs that can be cater on one
  PCM
               = 30/3 = 10
            Identities used in GSM
IMEI – International Mobile Equipment Identifier.

       IMEI = TAC + FAC + SNR +sp
  TAC = Type Approval Code by central GSM body
  FAC = Final Assembly Code, identifies the manufacturer
  SNR = Serial Number, unique six digit number
  sp = spare for future use
IMSI – International Mobile Subscriber Identifier

When a subscriber registers with a network operator, a unique
 subscriber IMSI identifier is issued and stored in the SIM
 of the MS as well as in the HLR . An MS can only
 function fully if it is operated with a valid SIM inserted
 into an MS with a valid IMEI. IMSI consist of three parts:
              IMSI = MCC + MNC + MSIN
  MCC = Mobile Country Code
  MNC = Mobile Network Code
  MSIN = Mobile Station Identification Number
TMSI –Temporary Mobile Subscriber Identity

A TMSI is used to protect the true identity (IMSI) of a
  subscriber. It is issued by and stored within a VLR (not in
  the HLR) when an IMSI attach takes place or a Location
  Area (LA) update takes place. At the MS it is stored in the
  MS’s SIM. The issued TMSI only has validity within a
  specific LA.

Since TMSI has local significance, the structure may be
   chosen by the administration. It should not be more than
   four octets.
MSISDN – Mobile Station ISDN Number

The MSISDN represents the ‘true’ or ‘dialled’ number
  associated with the subscriber. It is assigned to the
  subscriber by the network operator at registration and is
  stored in the SIM.

It is composed in the following way:
               MSISDN = CC + NDC + SN
    CC = Country Code
    NDC = National Destination Code
    SN = Subscriber Number
MSRN – Mobile Station Roaming Number

The MSRN is a temporary, location-dependant ISDN number
  issued by the parent VLR to all MSs within its area of
  responsibility. It is stored in the VLR and associated HLR
  but not in the MS. The MSRN is used by the VLR
  associated MSC for call routing within the MSC/VLR
  service area.
LAI – Location Area Identity

Each Location Area within the PLMN has an associated
  internationally unique identifier (LAI). The LAI is
  broadcast regularly by BTSs on the Broadcast Control
  channel (BCCH), thus uniquely identifying each cell with
  an associated LA.
              LAI = MCC + MNC + LAC
  MCC = Mobile Country Code, same as in IMSI
  MNC = Mobile Network Code, same as in IMSI
    LAC = Location Area Code, identifies a location area
  within a GSM PLMN network. Maximum length of LAC
  is 16 bits.
             GSM Channels
                        Half rate 11.4kbps
            Speech
  TCH
(traffic)               Full rate 22.8kbps
                                    2.4 kbps
              Data
                                    4.8 kbps
                                     9.6 kbps
             BCH            FCCH(Frequency correction)

                            SCH(Synchronization)
                             PCH(Paging)
             CCCH
                              RACH(Random Access)
  CCH                         AGCH(Access Grant)
(control)
                              SDCCH(Stand Alone)
            Dedicated
                             SACCH(Slow-associated)
                            FACCH(Fast-associated)
                                                   HIERARCHY OF FRAMES
    1 HYPER FRAME = 2048 SUPERFRAMES = 2 715 648 TDMA FRAMES ( 3 H 28 MIN 53 S 760 MS )

0         1       2        3      4       5        6                                                        2043   2044 2045 2046 2047


    TRAFFIC CHANNELS       1 SUPER FRAME = 1326 TDMA FRAMES ( 6.12 S )
                                        LEFT (OR) RIGHT
    1 SUPER FRAME = 51 MULTI FRAMES

0     1       2       3    4                                48       49 50                      SIGNALLING CHANNELS

                                                                                       1 SUPER FRAME = 26 MULTI FRAMES

                                                                 0                 1            2                              24        25
 1 MULTIFRAME = 26 TDMA FRAMES ( 120 ms )

0 1 2         3                                        24 25
                                                                                       1 MULTI FRAME = 51 TDMA FRAMES (235 .4 ms )
                                                                                   0 1 2            3   4                           48 49 50


 0 1          2   3       4 5     6   7       0   1     2   3        4       5 6        7 0
                      (4.615ms)       TDMA FRAME NO.
                       0                        1
1 TIME SLOT = 156.25 BITS
      ( 0.577 ms)                                 0 1       2    3           4 5        6   7       0   1     2    3   4   5        6   7 0
                                                                                                             (4.615 ms)
1 2 3 4               155 156                                            0                                         1
     1 bit =36.9 micro sec
               Mobility Management

• Location updating- normal,periodic, IMSI attach
• Paging
• Security Management
   – Preventing unauthorized users- authentication
   – Maintaining Privacy of users- ciphering
• Providing roaming facility
• MM functionality mainly handled by MS, HLR, MSC/VLR.
       MS Location Update (registration)
MS        BTS      BSC   (G)MSC   VLR   HLR
Action
                                         Channel Request (RACH)
                                         Channel Assignment (AGCH)

  TMSI + old LAI
                                         Location Update Request (SDCCH)
                                         Authentication Request (SDCCH)

                                         Authentication Response (SDCCH)

                                         Comparison of Authentication param

                                         Accept LUP and allocTMSI (SDCCH)

                                         Ack of LUP and TMSI (SDCCH)

                                         Entry of new area and identity into
                                         VLR and HLR

                                         Channel Release (SDCCH)
                          Security - Authentication

     MS
Ki          RAND
                                              Authentication center provides
                                              RAND to Mobile
     A3                                       AuC generates SRES using Ki
              SRES                            of subscriber and RAND
                                              Mobile generates SRES using
      MS                   BTS          AuC   Ki and RAND
                                              Mobile transmits SRES to BTS
                                              BTS compares received SRES
                        RAND
                                              with one generated by AuC
                                 SRES

              SRES

          Auth Result
                                Cell Selection
Purpose: get synchronization
with the GSM network
prior establishing any communication.
                                                         1
                                        1

                                                BTS-5
            1                   BTS-4                    1

                                                             2
                                   1                         3
BTS-3                                       5
                                                             4
                                                                 BTS-1

                                                 This cell
                       BTS-2
                        Immediate Assignment
     MS                           BTS                            BSC                MSC

            CHANNEL REQUEST
      1
                  RACH                      CHANNEL REQUIRED
                                      2
                                           CHANNEL ACTIVATION
                                                                 3     Immediate
                                            CHANNEL ACTIVATION         Assignment
                                      4
                                                  ACK.

          IMMEDIATE ASSIGNMENT            IMMEDIATE ASSIGNMENT
                                                                 5
                                  5             COMMAND
                 AGCH



           CM SERVICE REQUEST
      6
             SDCCH or TCH
OR
          LOCATION UPDAT. REQU.
      6
             SDCCH or TCH
Registration: the Very First Location Update

           1
                                 BSS
         IMSI                                 2
   2                                                4                MSC
               4                       BSC        TMSI
                                                             5
       TMSI                                              6
                       5   BTS                                   2
       Release
                   6
                                                                     4     TMSI
                                                                           5

 LAI                                         HLR                     VLR
                                         IMSI                3           IMSI
                                         VLR id                          TMSI
                                                                         LAI
                          IMSI Attach
       CHANNEL
 1
       REQUEST                  BSS
     IMMEDIATE
                      2
     ASSIGNMENT

3 LOCATION UPDATING                   BSC   3
 REQUEST (IMSI Attach)
   Authentication         BTS                   4
   Procedure
                  4                                         MSC
 LOCATION UPDATING
                                                    5
                    5
 ACCEPT (LAC, TMSI)

                                                            4


                                                            VLR

                                                        6
                                   Mobile Originating Call
        MS                               BSS                            MSC                      PSTN
                   CHANNEL REQUEST                                                  VLR
   Dialing 1
                  IMMEDIATE ASSIGNMENT
                                          2
                   CM SERVICE REQUEST             CM SERVICE REQUEST
              2                               2

                              3     Authentication procedure

                          3         Ciphering procedure

  Sending           SETUP (basic) or                    SETUP
              4                                   4
  Number            EMERGENCY                                                   5
                                                                                          IAM
                                                  CALL PROCEEDING           6                             Ring
                  CALL PROCEEDING                                      7
                                         7
                                                                                                                 Ringing
                      7           Assignment procedure
                                                                                       ACM
                                                        ALERTING 9                               8
   Ringing
                                                                                       ANM
   Path                                               CONNECT
                                                                       11
                                                                                                 10
Established
                                              CONNECT ACKnowledge                   ACM = Address Complete Message
              11                                                                    ANM = ANswer Message
                                                                                    IAM = Initial Address Message
                  Mobile Terminating Call
                   1 - Paging Principle
LA1


                        6       BSC1        4
        BTS11
                                       5
                                                  3          1
BTS12                                      MSC/                  PSTN
                            6                         GMSC
                                       5   VLR
                                BSC2
        BTS21
                                                      2
                BTS22
                                                      HLR
LA2
        BTS23                   BSC3


                BTS31
                               Mobile Terminating Call
                                2 - Detailed Procedure
                Visitor PLMN                               International           Home PLMN
                                                                SS7
                                        VLR                                                  HLR
                                                      Provide Roaming Number
                                                               (IMSI)               4

                                                          Roaming Number
                                                5             (MSRN)
                                                                                         6
                                    9
                                                                                                   Send            1
                                              Send info                        Routing             Routing
                           PAGE               to I/C
 PAGING                                                                    Information             Information         MSISDN
                      (TMSI + LA)             (MSRN)
REQUEST                                                                        (MSRN)              (MSISDN)
   (TMSI)
                                          8                                                    3
        11         PAGING                                   IAM (MSRN)
                  REQUEST                                                                             IAM
                             10     VMSC                                           7     GMSC                2    ISDN
       BSS       (TMSI + LA)                                                                        (MSISDN)
                                                               PN


   IAM       : Initial Address Message                          IMSI       :   International Mobile Subscriber Identity
   MSISDN    : Mobile Station Integrated Services Digital       GMSC       :   Gateway MSC
               network Number                                   VMSC       :   Visitor MSC
   MSRN      : Mobile Station Roaming Number                    TMSI       :   Temporary Mobile Subscriber Identity
                                  Call Release

MS                        BSS                        MSC               PSTN


                   1              Call in progress

         DISCONNECT
 2                                  DISCONNECT
                              2


         RELEASE                   RELEASE
                                                     3
                          3

                RELEASE COMPLETE
     4
                                                             Release
     CHANNEL RELEASE 6                                   5


     RELEASE INDICATION
 7

     RF Channel Release
     procedure      8
                                                                              Release
                                                                          9
                                                                              tone
         Discontinuous Transmission

• Discontinuous Transmission(DTX) allows the radio
  transmitter to be switched off most of the time during
  speech pauses.
• A Silence Indicator Block is transmitted at 500bps,
  which generates a comfort noise
• Down Link interference is decreased.
• Up link battery is saved
DRIVE TEST

 What is Drive Test?



 Drive test involves setting up a call to best carrier
 and driving along the roads.


 While driving, the radio parameters and air
 Interference signal data are collected as a log file.
              Drive Test Setup
Drive Test system comprises of

 A Test mobile phone :Single or Dual Band.
with Netmonitor software

 SIM Card : Test SIM.

 Laptop:Min config. 1GB RAM,1GB HD

 Software to control and log data from the phone.:Depend on different
vendor

 Global Positioning System(GPS) receiver for position information

 PCMCIA Card/USB Hub: To add more Ports.

 Local Maps :Indicating all site-mark, with BCCH/BSIC values.

 Transportation: Car with Charger

 External Antenna for Test mobile phone can also be used for drive test

Battery Charger Or Inverter
     contd..
         Objective of Drive test
Following steps are taken to fulfill the objective of using a drive test tool.

To verify whether the network meets the given requirements, on the basis of
which network was designed.

 To verify whether the parameters and configurations are defined correctly or
not.

 To investigate network problems related to poor quality, signal level,
Interference etc…

 Tune and optimize networks

 Perform fault-tracing and troubleshooting
contd..
     Rx Level Plot
Rx Quality Plot
     contd..
                     RxQual measurement
RXQUAL, is the Bit error rate (BER) derived from the 26 bits Mid amble on
TDMA burst. Speech quality is inferred by the RXQUAL measurements during
the drive test. Its level characterizes speech quality where 0 indicates the highest
quality and 7 the worst.
BER = Errors/Total Number of Bits

Thus during drive test, poor quality areas can be found and marked by looking
over the quality on the scale of 0 to 7.
RXQUAL can be poor due to poor RXLEV, Co-channel interference, adjacent
channel interference or Multipath.
                                              Quality        BER         Comments
                                                0       less than 0.2%     Good
                                                1        0.2% to 0.4%      Good
                                                2        0.4% to 0.8%      Good
                                                3        0.8% to 1.6%      Good
                                                4        1.6% to 3.2%      Good
                                                5        3.2% to 6.4%      Bad
                                                6       6.4% to 12.8%      Bad
                                                7     greater than 12.8%   Bad
contd..
     RX Level Measurement
       6 classes for Level dimension (7 levels)


    -47dBm                                        level 63

              Class 63
    -70dBm                                        level 40

              Class 40
    -80dBm                                        level 30

              Class 30
    -90dBm                                        level 20

              Class 20
    -95dBm                                        level 15

              Class 15
    -100dBm                                       level 10

              Class 10
    -110dBm                                       level 0
                ANTENNA DOWNTILTING
 Antenna downtilting is the downward tilt of the vertical pattern towards
  the ground by a fixed angle measured w.r.t the horizon.
 Downtilting of the antenna changes the position of the half-power
  beamwidth and the first null relative to the horizon.
 Normally the maximum gain is at 0• tilt (parallel to the horizon) and
  never intersects the horizon.
With appropriate downtilt, the received signal strength within the cell
  improves due to the placement of the main lobe within the cell radius and
  falls off in regions approaching the cell boundary and towards the reuse
  cell.
 There are two methods of downtilting
      Mechanical downtilting
      Electrical downtilting.
contd..
MECHANICAL DOWNTILTING
THANK YOU
QUESTIONS?

				
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